Increasing an electrical resistance of a resistor by oxidation or nitridization

ABSTRACT

A method and structure for increasing an electrical resistance of a resistor that is within a semiconductor structure, by oxidizing or nitridizing a fraction of a surface layer of the resistor with oxygen/nitrogen (i.e., oxygen or nitrogen) particles, respectively. The semiconductor structure may include a semiconductor wafer, a semiconductor chip, and an integrated circuit. The method and structure comprises five embodiments. The first embodiment comprises heating an interior of a heating chamber that includes the oxygen/nitrogen particles as gaseous oxygen/nitrogen-comprising molecules (e.g., molecular oxygen/nitrogen). The second embodiment comprises heating the fraction of the surface layer by a beam of radiation (e.g., laser radiation), or a beam of particles, such that the semiconductor structure is within a chamber that includes the oxygen/particles as gaseous oxygen/nitrogen-comprising molecules (e.g., molecular oxygen/nitrogen). The third embodiment comprises: using a plasma chamber to generate plasma oxygen/nitrogen ions; and applying a DC voltage to the plasma oxygen/nitrogen ions to accelerate the plasma oxygen/nitrogen ions into the resistor such that the oxygen/nitrogen particles include the plasma oxygen/nitrogen ions. The fourth embodiment comprises using an anodization circuit to electrolytically generate oxygen/nitrogen ions in an electrolytic solution in which the resistor is immersed, wherein the oxygen/nitrogen particles include the electrolytically-generated oxygen/nitrogen ions. The fifth embodiment comprises immersing the semiconductor structure in a chemical solution which includes the oxygen/nitrogen particles, wherein the oxygen/nitrogen particles may include oxygen/nitrogen-comprising liquid molecules, oxygen/nitrogen ions, or an oxygen/nitrogen-comprising gas dissolved in the chemical solution under pressurization.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention provides a method and structure forincreasing an electrical resistance of a resistor that is located withina semiconductor structure such as a semiconductor wafer, a semiconductorchip, and an integrated circuit.

[0003] 2. Related Art

[0004] A resistor on a wafer may have its electrical resistance trimmedby using laser ablation to remove a portion of the resistor. Forexample, the laser ablation may cut slots in the resistor. With existingtechnology, however, trimming a resistor by using laser ablationrequires the resistor to have dimensions on the order of tens ofmicrons. A method and structure is needed to increase the electricalresistance of a resistor on a wafer generally, and to increase theelectrical resistance of a resistor having dimensions at a micron orsub-micron level.

SUMMARY OF THE INVENTION

[0005] The present invention provides a method for increasing anelectrical resistance of a resistor, comprising the steps of:

[0006] providing a semiconductor structure that includes the resistor;and

[0007] oxidizing a fraction F of a surface layer of the resistor withoxygen particles, resulting in the increasing of the electricalresistance of the resistor.

[0008] The present invention provides an electrical structure,comprising:

[0009] a semiconductor structure that includes a resistor; and

[0010] oxygen particles in an oxidizing reaction with a fraction F of asurface layer of the resistor, wherein the oxidizing reaction increasesan electrical resistance of the resistor.

[0011] The present invention provides a method for increasing anelectrical resistance of a resistor, comprising the steps of:

[0012] providing a semiconductor structure that includes the resistor;and

[0013] nitridizing a fraction F of a surface layer of the resistor withnitrogen particles, resulting in the increasing of the electricalresistance of the resistor.

[0014] The present invention provides an electrical structure,comprising:

[0015] a semiconductor structure that includes a resistor; and

[0016] nitrogen particles in an nitridizing reaction with a fraction Fof a surface layer of the resistor, wherein the nitridizing reactionincreases an electrical resistance of the resistor.

[0017] The present invention provides a method and structure forincreasing an electrical resistance of a resistor on a wafer generally,and for increasing the electrical resistance of a resistor havingdimensions at a micron or sub-micron level.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 depicts a front cross-sectional view of a semiconductorstructure that includes an electrical resistor, in accordance withembodiments of the present invention.

[0019]FIG. 2 depicts FIG. 1 at an onset of exposure of a portion of theresistor to oxygen particles.

[0020]FIG. 3 depicts FIG. 2 after exposure of the portion of theresistor to the oxygen particles.

[0021]FIG. 4 depicts a front cross-sectional view of a heating chamberthat includes the semiconductor structure of FIG. 2 and anoxygen-comprising gas, wherein the heating chamber generates heat thatheats the semiconductor structure, in accordance with embodiments of thepresent invention.

[0022]FIG. 5 depicts a front cross-sectional view of a chamber thatincludes the semiconductor structure of FIG. 2 and an oxygen-comprisinggas, wherein the resistor of the semiconductor structure is heated by adirected beam of radiation or particles, in accordance with embodimentsof the present invention.

[0023]FIG. 6 depicts a front cross-sectional view of a plasma chamberthat includes the semiconductor structure of FIG. 2, in accordance withembodiments of the present invention.

[0024]FIG. 7 depicts a front cross-sectional view of an anodization bathin which the semiconductor structure of FIG. 2 is partially immersed, inaccordance with embodiments of the present invention.

[0025]FIG. 8 depicts a front cross-sectional view of a chemical bath inwhich the resistor of the semiconductor structure of FIG. 2 is immersed,in accordance with embodiments of the present invention.

[0026]FIG. 9 depicts FIG. 2 during exposure of the portion of theresistor to the oxygen particles, and with the resistor coupled to anelectrical resistance measuring apparatus, in accordance withembodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0027]FIG. 1 illustrates a front cross-sectional view of a semiconductorstructure 10 that includes an electrical resistor 14 within asemiconductor substrate 12, in accordance with embodiments of thepresent invention. The electrical resistor 14 includes an electricallyresistive material. The semiconductor structure 10 may include, interalia, a semiconductor wafer, a semiconductor chip, an integratedcircuit, etc. The substrate 12 comprises all portions of thesemiconductor structure 10 (e.g., electronic devices includingsemiconductor devices, wiring levels, etc.) exclusive of the resistor14. The resistor 14 may have any electrical resistance functionalitywithin the semiconductor substrate 12 and accordingly may exist within asemiconductor device, within an electrical circuit, etc. The resistor 14includes an exposed surface 19 having a surface area S.

[0028]FIG. 2 illustrates FIG. 1 at an onset of exposure of a portion 15of the resistor 14 to oxygen particles 20. The oxygen particles 20 maycomprise oxygen-comprising molecules (e.g., molecular oxygen O₂, carbondioxide CO₂, etc.) or oxygen ions, depending on which of severalembodiments of the present invention is operative, as will be discussedinfra. The oxygen-exposed portion 15 has an oxygen-exposed surface 17(i.e.; the surface 17 is exposed to the oxygen particles 20). Theresistor 14 includes an oxygen-unexposed portion 16 that has anoxygen-unexposed surface 18 (i.e.; the surface 18 is unexposed to theoxygen particles 20). The surface 19 (see FIG. 1) comprises the surfaces17 and 18 which have surface areas S_(E) and S_(U), respectively. Thusthe surface area S of the surface 19 (see FIG. 1) is S_(E)+S_(U). InFIG. 2, the oxygen-unexposed portion 16 and the associated surface 18,if present, gives rise to a “partially exposed” embodiment, since thesurface 19 will be partially exposed to the oxygen particles 20 (at thesurface 17) such that S_(U)>0. The oxygen-unexposed portion 16 and theassociated surface 18, if not present, gives rise to a “totally exposed”embodiment, since the surface 19 will be totally exposed to the oxygenparticles 20 (at the surface 17) such that S_(U)=0.

[0029]FIG. 3 illustrates FIG. 2 after the exposure of the portion 15 ofthe resistor 14 to the oxygen particles 20. The exposure of the portion15 of the resistor 14 for a finite time of exposure generates anoxidized region 22 within the portion 15, wherein an unoxidized portion24 of the resistor 14 remains. The oxidized region 22 is a fraction F ofa surface layer of the resistor 14, wherein the surface layer is aregion defined as the oxidized region 22 projected to the side surfaces25 and 26 of the resistor 14. The fraction F is in a range of 0<F≦1,wherein 0<F<1 corresponds to the “partially exposed” embodiment, and F=1corresponds to the “totally exposed” embodiment, discussed supra. Theoxidized region 22 has a thickness t that may increase as the time ofexposure increases or may reach a self-limiting thickness. For oxidationprocesses which are diffusion dominated, the thickness t may vary, interalia, as a square root of the time of exposure. The oxidized region 22increases an electrical resistance of the resistor 14 associated withcurrent flow either in a direction 6 or in a direction 7, in comparisonwith an electrical resistance of the resistor 14 that existed before theoxidized region 22 was formed.

[0030] The resistor 14 could be within an integrated circuit and,accordingly, FIG. 3 also shows in of the integrated circuit above theresistor 14. The insulative layer 11 includes an insulative material 13and an opening 23, wherein the opening 23 which defines the resistor 14that is potentially oxidizable in accordance with the present invention.Note that there may be resistive regions 28 underneath the insulativematerial 13 and thus blocked by the insulative material 13. Accordingly,the underneath or blocked resistive regions 28 are not oxidizable inaccordance with the present invention. Although not explicated ordiscussed in the embodiments described infra, the resistor 14 could bethought of as being “partially exposed” if the total resistor is definedas the resistor 14 in combination with the underneath or blockedresistive regions 28.

[0031] The present invention includes five embodiments for oxidizing theresistor 14 to increase the electrical resistance of the resistor 14,namely: thermal oxidation using a heating chamber (FIG. 4); thermaloxidation using a direct beam of radiation or particles (FIG. 5); plasmaoxidation (FIG. 6); anodization (FIG. 7); and chemical oxidation (FIG.8). The following discussion will describe these embodiments and explainhow in situ testing can be used to control the electrical resistanceacquired by the resistor 14 after being exposed to the oxygen particles20 (FIG. 9).

[0032] While the five embodiments mentioned supra and discussed infraspecifically describe oxidizing the resistor 14, the five embodimentsmentioned supra and discussed infra are each applicable to changing anthe resistance of the resistor 14 by nitridizing as an alternative tooxidizing. Nitridizing the resistor 14, as opposed to oxidizing theresistor 14, means reacting the resistor 14 with nitrogen particles(instead of with the oxygen particles 20) in a manner that forms anitride of the electrically resistive material of the resistor 14comprises (instead of forming an oxide of electrically resistivematerial that the resistor 14). As with the oxygen particles 20, thenitrogen particles may be in molecular or ionic form depending on theoperative embodiment. “Partially exposed” and “fully exposed”embodiments are applicable to nitridization of the resistor 14, just as“partially exposed” and “fully exposed” embodiments are applicable tooxidation of the resistor 14. Unless noted otherwise herein, allfeatures and aspects of the five embodiments, as discussed infra, applyto nitridization of the resistor 14 just as said all features andaspects of the five embodiments apply to oxidation.

[0033] Thermal Oxidation Using a Heating Chamber

[0034]FIG. 4 illustrates a front cross-sectional view of a heatingchamber 30 that includes an oxygen-comprising gas 32 and thesemiconductor structure 10 of FIG. 2, in accordance with embodiments ofthe present invention. The gas 32 includes an oxygen compound such as,inter alia, molecular oxygen (O₂), nitrous oxide (N₂O), carbon dioxide(CO₂), and carbon monoxide (CO).

[0035] The heating chamber 30 is heated to a heating temperature and theresistor 14 is thus oxidized by the gas 32 to form an oxide regionwithin the resistor 14 such as the oxide region 22 depicted supra inFIG. 3. A thickness of the oxidized region (see, e.g., the thickness tof the oxidized region 22 described supra for FIG. 3) increases as atime of exposure of the resistor 14 to the gas 32 increases. FIG. 4exemplifies a “totally exposed” embodiment in which the oxygen-unexposedportion 16 (see FIG. 2) of the resistor 14 does not exist (i.e., S_(U)=0and F=1), and the surface 17 is the total surface 19 (see FIG. 1) thatis oxidized. In FIG. 4, the oxygen concentration in the ambient gas 32and the heating temperature, in combination, should be sufficient tooxidize the resistor 14. Said combinations depend on the chemistry ofthe oxidizing reaction between the resistor 14 and the gas 32. Thus, therequired oxygen concentration and heating temperature depends on amaterial composition of the resistor 14 and the gas 32.

[0036] The gas 32 may be non-flowing in the form of a volumetricdistribution within the heating chamber 30. Alternatively, the gas 32may be in a flowing form at low flow, wherein the gas 32 contacts theresistor 14. Since the flowing gas 32 originates from a source that islikely to be substantially cooler than the heating temperature, theoxygen flow rate should be sufficiently slow as to minimize orsubstantially eliminate heat transfer from the resistor 14 to the gas32. Such inhibition of heat transfer may by any method known to one ofordinary skill in the art. One such method is for the oxygen flow to beslow enough that the dominant mode of said heat transfer is by naturalconvection rather than by forced convection. An additional alternativeusing flowing oxygen includes preheating the gas 32 to a temperaturesufficiently close to the heating temperature so that said heat transferis negligible even if said heat transfer occurs by forced convection.

[0037] The heating chamber 30 in FIG. 4 includes any volumetricenclosure capable of heating the semiconductor structure 10 placedtherein. The heat within the heating chamber 30 may be directed towardthe semiconductor structure 10 in the direction 37 from a heat source 34above the semiconductor structure 10. The heat within the heatingchamber 30 may also be directed toward the semiconductor structure 10 inthe direction 38 from a heat source 36 below the semiconductor structure10. Heat directed from the heat source 34 in the direction 37 istransferred to the surface 17 more directly than is heat directed fromthe heat source 36 in the direction 38. Accordingly, the heat directedfrom the heat source 34 in the direction 37 is more efficient forraising the temperature at the surface 17 than is the heat directed fromthe heat source 36 in the direction 38. Either or both of the heatsources 34 and 36 may be utilized in the heating chamber 30. Either orboth of the heat sources 34 and 36 may be a continuous heat source or adistributed array of discrete heat sources such as a distributed arrayof incandescent bulbs. Alternatively, the heating chamber 30 may be afurnace.

[0038] Any method of achieving the aforementioned heating temperature inthe heating chamber 30 is within the scope of the present invention. Forexample, the semiconductor structure 10 could be inserted into theheating chamber 30 when the heating chamber 30 is at ambient roomtemperature, followed by a rapid ramping up of temperature within theheating chamber 30 until the desired heating temperature is achievedtherein. If the heating temperature is spatially uniform at and near theresistor 14, then the oxidation of the resistor 14 in the direction 37will be spatially uniform such that a thickness of the resultant oxidelayer is about constant (see, e.g., the thickness t of the oxide layer22 in FIG. 3 which is about constant). A spatially nonuniform heatingtemperature which would result in a oxide layer thickness that is notconstant. Both uniform and nonuniform heating temperature distributions,and consequent uniform and nonuniform oxide layer thicknesses, arewithin the scope of the present invention.

[0039] Suitable resistor 14 electrically resistive materials for beingoxidized in the heating chamber 30 include, inter alia, one or more ofpolysilicon, amorphous silicon, titanium, tantalum, tungsten, aluminum,silver, copper, or nitrides, silicides, or alloys thereof.

[0040] The aforementioned method of oxidizing the resistor 14 using theheating chamber 30 does not depend on the dimensions of the resistor 14and is thus applicable if the resistor 14 has dimensions of 1 micron orless, and is likewise applicable if the resistor 14 has dimensions inexcess of 1 micron.

[0041] As stated supra, thermal nitridization using a heating chambercould be used as an alternative to thermal oxidation using a heatingchamber. If nitridization is employed, the gas 32 would include, insteadof an oxygen compound, a nitrogen compound such as, inter alia,molecular nitrogen (N₂).

[0042] Thermal Oxidation Using a Directed Beam of Radiation or Particles

[0043]FIG. 5 illustrates a front cross-sectional view of a chamber 40that includes the semiconductor structure 10 of FIG. 2 and anoxygen-comprising gas 42, wherein the resistor 14 of the semiconductorstructure 10 is heated by a directed beam 46 of radiation or particles,in accordance with embodiments of the present invention. The gas 42includes an oxygen compound such as, inter alia, molecular oxygen (O₂),nitrous oxide (N₂O), carbon dioxide (CO₂), and carbon monoxide (CO). Thegas 42 may be non-flowing or flowing as discussed supra in conjunctionwith the gas 32 of FIG. 4

[0044] The portion 15 of the resistor 14 is heated to a heatingtemperature by the directed beam 46, and the portion 15 is thus oxidizedby the gas 32 to form an oxide region within the resistor 14 such as theoxide region 22 depicted supra in FIG. 3. A thickness of the oxidizedregion (see, e.g., the thickness t of the oxidized region 22 describedsupra for FIG. 3) increases as a time of exposure of the resistor 14 tothe directed beam 46 increases. The thickness of the oxidized regionalso increases as an energy flux of the directed beam 46 increases. Thedirected beam 46 may include radiation (e.g., laser radiation), oralternatively, a beam of particles (e.g., electrons, protons, ions,etc.). The directed beam 46 must be sufficiently energetic to providethe required heating of the resistor 14, and a minimum required energyflux of the directed beam 46 depends on a material composition of theresistor 14. Additionally, the directed beam 46 should be sufficientlyfocused so that the aforementioned energy flux requirement is satisfied.

[0045] If the directed beam 46 includes laser radiation, then the laserradiation may comprise a continuous laser radiation or a pulsed laserradiation. If the resistor 14 comprises a metal, then the presentinvention will be effective for a wide range of wavelengths of the laserradiation, since a metal is characterized by a continuum of energylevels of the conduction electrons rather than discrete energy levelsfor absorbing the laser radiation.

[0046] The directed beam 46, which is generated by a source 44, may bedirected to the oxygen-exposed portion 15 of the resistor 14 in a mannerthat the oxygen-unexposed portion 16 of the resistor 14 exists. Forexample, the source 44 may include a laser whose spot size area is lessthan the surface area S of the total surface 19 (see FIG. 1) of theresistor 14, and the associated directed beam 46 includes radiation fromthe laser of the source 44. Thus it is possible for the laser beam totraverse less than the total surface 19. Similarly, the source 44 maygenerate the directed beam 46 as the beam of particles, which impartenergy to the resistor 14 and thus heat the resistor 14. The directedbeam 46 may be localized to the surface 17 which requires that thedirected beam 46 be sufficiently anisotropic; i.e., sufficientlylocalized to the direction 37 by the source 44, which depends onphysical and operational characteristics of the source 44. Accordingly,if the directed beam 46 is localized to the surface 17, then FIG. 5would exemplify a “partially exposed” embodiment in which theoxygen-unexposed portion 16 (see FIG. 2) exists (i.e., S_(U)>0 and F<1).Alternatively, FIG. 5 may also exemplify a “totally exposed” embodimentin which the oxygen-unexposed portion 16 (see FIG. 2) does not exist(i.e., S_(U)=0 and F=1), since the directed beam 46 could be directed tothe total surface 19. Thus, FIG. 4 exemplifies either a “totallyexposed” (F=1) or a “partially exposed” (F<1) embodiment in which theoxygen-unexposed portion 16 (see FIG. 2) may or may not exist. A spatialextent of partial or total exposure to, and associated reaction with,the oxygen-comprising gas 42 may be controlled by adjusting the size(i.e., area) of the directed beam 46 and/or by scanning the directedbeam 46 across portions of the total surface 19 (see FIG. 1).

[0047] In FIG. 5, the oxygen concentration in the gas 32 and the heatingtemperature, in combination, should be sufficient to oxidize theresistor 14, and depends on the chemistry of the oxidizing reactionbetween the resistor 14 and the gas 32 as discussed supra in conjunctionwith FIG. 4. An ability to achieve the required temperature depends onthe directed beam 46 being sufficiently energetic so as to impart enoughenergy to the portion 15 of the resistor 14 to facilitate the heatingand consequent oxidation of the portion 15. The energy of the directedbeam 46 is controlled at its source 44.

[0048] As stated supra, an advantage of using the directed beam 46 ofFIG. 5 instead of the heating chamber 30 of FIG. 4 to heat the resistor14 is the ability to heat less than the total exposed surface area 19 ofthe resistor 14. Another advantage is that said heating of thesemiconductor structure 10 by the heating chamber 30 could potentiallydamage thermally-sensitive portions of the semiconductor structure 10which cannot tolerate the temperature elevation caused by the heatingchamber 30. In contrast, the localized heating by the directed beam 46advantageously does not expose said thermally-sensitive portions of thesemiconductor structure 10 to potential thermally-induced damage.

[0049] Suitable resistor 14 electrically resistive materials for beingoxidized while being heated by the directed beam 46 include, inter alia,one or more of polysilicon, amorphous silicon, titanium, tantalum,tungsten, aluminum, silver, copper, or nitrides, silicides, or alloysthereof.

[0050] If the directed beam 46 is required to be confined to the surface19 (see FIG. 1) of the resistor 14 (i.e., if the directed beam 46 shouldnot strike any surface of the resistor 14 other than the surface 19),then dimensions of the surface 19 should be no smaller than a smallestsurface area on which the directed beam 46 could be focused. Forexample, if the directed beam 46 includes laser radiation and the source44 includes a laser, then the dimensions of the portion 15 of theresistor 14 may be no smaller than a laser spot dimension. Since withcurrent and future projected technology, laser spot dimensions of theorder of 1 micron or less are possible, the portion 15 of the resistor14 may have dimensions of 1 micron or less (to an extent possible withprevailing laser technology at a time when the present invention ispracticed), as well as dimensions exceeding 1 micron, when the directedbeam 46 includes the laser radiation.

[0051] As stated supra, thermal nitridization using a directed beam ofradiation or particles could be used as an alternative to thermaloxidation using a directed beam of radiation or particles. Ifnitridization is employed, the gas 42 would include, instead of anoxygen compound, a nitrogen compound such as, inter alia, molecularnitrogen (N₂).

[0052] Plasma Oxidation

[0053]FIG. 6 illustrates a front cross-sectional view of a plasmachamber 50 that comprises the semiconductor structure 10 of FIG. 2, inaccordance with embodiments of the present invention. The plasma chamber50 includes an electrode 54 and an electrode 55. The semiconductorstructure 10 has been disposed between the electrode 54 and theelectrode 55. The plasma chamber 50 also includes oxygen ions 52 whichare formed in generation of a plasma gas, as will be explained infra.

[0054] A neutral gas within the plasma chamber 50 includes an oxygencompound such as, inter alia, molecular oxygen (O₂), nitrous oxide(N₂O), carbon dioxide (CO₂), and carbon monoxide (CO). Inasmuch as aplasma gas will be formed from the neutral gas, the plasma chamber 50may also include one or more noble gases (e.g., argon, helium, nitrogen,etc.) to perform such functions as: acting as a carrier gas, providingelectric charge needed for forming ionic species of the plasma,assisting in confining the plasma to within fixed boundaries, assistingin developing a target plasma density or a target plasma density range,and promoting excited state plasma lifetimes.

[0055] A power supply 56 generates an electrical potential between theelectrode 54 and the electrode 55. The power supply 56 may be of anytype known to one skilled in the art such as, inter alia: a radiofrequency (RF) power supply; a constant voltage pulsed power supply(see, e.g., U.S. Pat. No. 5,917,286, June 1999, Scholl et al.); and adirect current (DC) voltage source (see, e.g., U.S. Pat. No. 4,292,384,September 1981, Straughan et al.). Pertinent characteristics of thepower supply 56 are in accordance with such characteristics as are knownin the art. For example, a RF power supply may include, inter alia, aradio frequency selected from a wide range of frequencies such as acommonly used frequency of 13.56 Hz. The power requirements of the RFpower supply depends on the surface area 17 of the resistor 14 and isthus case dependent. For example, a typical range of power of the RFpower supply may be, inter alia, between about 100 watts and about 2000watts.

[0056] The electrical potential generated by the power supply 56 ionizesthe neutral gas to form a plasma between the electrode 54 and theelectrode 55, wherein the plasma comprises electrons and ions, andwherein a plasma ion polarity depends on the particular neutral gaswithin the plasma chamber 50. For example, if the neutral gas includesmolecular oxygen, then a three-component plasma may be formed includingelectrons, positive oxygen ions, and negative oxygen ions, such that inthe glow discharge a predominant positive ion is O₂ ⁺ and a lesserpositive ionic species is O⁺. See U.S. Pat. No. 5,005,101 (Gallagher etal.; April 1991; col. 6, lines 1-12).

[0057] In FIG. 6, a DC power supply 57 has terminals 58 and 59, whereinthe terminal 58 is positive with respect to a ground 51, and theterminal 59 is negative with respect to the terminal 58. The DC powersupply 57 generates an electric field that is directed from theelectrode 54 to the electrode 55, and the electric field is capable ofaccelerating positive ions from the electrode 54 toward the electrode 55in the direction 37. Accordingly, if the oxygen ions 52 are positiveoxygen ions (e.g., O₂ ⁺), then the electric field accelerates the oxygenions 52 of the plasma toward the electrode 55 causing the oxygen ions 52to strike the portion 15 of the resistor. If the oxygen ions 52 aresufficiently energetic (i.e., if the oxygen ions 52 have a minimum orthreshold energy) as required to oxidize the portion 15 of the resistor14, then the oxygen ions 52 will so oxidize the portion 15 and thus forman oxidized region within the resistor 14, such as the oxidized region22 depicted supra in FIG. 3. A thickness of the oxidized region (see,e.g., the thickness t of the oxidized region 22 described supra for FIG.3) increases as a time of exposure of the resistor 14 to the acceleratedoxygen ionic species 52 increases.

[0058] If the oxygen ions 52 are negative oxygen ions to be acceleratedtoward the resistor 14 and reacted with the resistor 14, then thepolarities of the terminals 58 and 59 should be reversed (i.e., theterminals 58 and 59 should have negative and positive polarities,respectively). A factor in determining whether positive or negativeoxygen ions 52 are to be reacted with the resistor 14 includesconsideration of the chemical reactions between said accelerated oxygenions 52 and the electrically resistive material of the resistor 14,since characteristics of said chemical reactions (e.g., reactionenergetics, reaction rate, etc.) may be a function of the polarity ofthe reacting ionic oxygen species 52. Nonetheless, if negative oxygenions 52 of the plasma are accelerated by the DC power supply 57 towardthe resistor 14, then electrons of the plasma will also be acceleratedtoward the resistor 14, which in some situations may result inundesirable interactions between said electrons and the resistor 14.Thus, each of the aforementioned considerations (e.g., material of theresistor 14, characteristics of the chemical reactions between theoxygen ions 52 and the resistor 14, etc.) must be considered whenchoosing the neutral gas and choosing which ionic species 52 to reactwith the resistor 14.

[0059] The accelerated oxygen ions 52 transfer energy to the resistor 14to provide at least the threshold energy required for effectuating thechemical reaction between the oxygen ions 52 and the resistor 14, andsuch energy transferred substitutes for thermal energy (i.e., heat)provided by the heating chamber 30 of FIG. 4, or by the directed beam 46of radiation or particles of FIG. 5, to the resistor 14. A voltageoutput of the DC power supply 57 must be sufficient to accelerate theoxygen ions 52 to at least the aforementioned threshold energy.

[0060]FIG. 6 exemplifies a “totally exposed” embodiment in which theoxygen-unexposed portion 16 (see FIG. 2) of the resistor 14 does notexist (i.e., S_(U)=0 and F=1), and the surface 17 is the total surface19 (see FIG. 1) that is oxidized in the plasma chamber 50.

[0061] While FIG. 6 depicts a particular plasma chamber 50 configurationfor oxidizing the resistor 14, any plasma configuration known to one ofordinary skill in the art may be used.

[0062] Suitable resistor 14 electrically resistive materials for beingsubject to plasma oxidation include, inter alia, one or more ofpolysilicon, amorphous silicon, titanium, tantalum, tungsten, aluminum,silver, copper, or nitrides, suicides, or alloys thereof.

[0063] The aforementioned method of oxidizing the resistor 14 usingplasma oxidation does not depend on the dimensions of the resistor 14and is thus applicable if the resistor 14 has dimensions of 1 micron orless, and is likewise applicable if the resistor 14 has dimensions inexcess of 1 micron.

[0064] As stated supra, plasma nitridization using a directed beam ofradiation or particles could be used as an alternative to plasmaoxidation using a directed beam of radiation or particles. Ifnitridization is employed, the neutral gas within the plasma chamber 50would include, instead of an oxygen compound, a nitrogen compound suchas, inter alia, molecular nitrogen (N₂).

[0065] Anodization

[0066]FIG. 7 illustrates a front cross-sectional view of an anodizationbath 60, in accordance with embodiments of the present invention.Generally, anodizing a first conductive material such as a semiconductoror metal requires immersing into an electrolytic solution both the firstconductive material and a second conductive material, and passing a DCcurrent at a sufficient voltage through the electrolytic solution.

[0067] An anodization electrical circuit 69 includes a DC power supply64, an electrolytic solution 61 which includes oxygen, the semiconductorstructure 10 of FIG. 2 wherein the resistor 14 is partially immersed inthe electrolytic solution 61, and an electrode 63 partially immersed inthe electrolytic solution 61. “Partially immersed” includes “totallyimmersed” (i.e., 100% immersed) as a special case. The resistor 14 ismade of the electrically resistive material which includes the firstconductive material that serves as an anode, and the electrode 63 ismade of the second conductive material that serves as a cathode. Thesecond conductive material of the cathode may include any inert metal(e.g., platinum) that does not react with the electrolytic solution 61.The resistor 14 is made anodic by electrically coupling the resistor 14to a positive terminal 65 of the DC power supply 64. The electrode 63 ismade cathodic by electrically coupling the electrode 63 to a negativeterminal 66 of the DC power supply 64. The anodization may be performedat or above ambient room temperature. A thickness of an oxide filmformed with the resistor 14 is a function of a voltage output from theDC power supply 64 and the current density in the anodization circuit69. The specific voltage and current density is application dependentand would be selected from known art by one of ordinary skill in theart. For example, an anodization of tantalum or tantalum nitride atambient room temperature and at with a current density of about 0.1milliamp/cm² in an electrolytic solution of citric acid will generate anoxide (i.e., tantalum pentoxide Ta₂O₅) film thickness of 20 Å per volt.Thus for an applied voltage of about 25 volts, the Ta₂O₅ film thicknessis about 500 Å.

[0068] Suitable resistor 14 electrically resistive materials for beinganodized include, inter alia. Suitable cathode 63 materials include,inter alia tantalum, titanium, polysilicon, aluminum, tungsten, nitridesthereof, and alloys thereof. A electrolyte containing oxygen that can beused depends on the electrically resistive material to be anodized andis therefore case specific. Thus, any electrolyte containing oxygen thatis compatible with said electrically resistive material may be selectedas would be known or apparent to one of ordinary skill in the art.

[0069] Upon activation of the DC power supply 64 (i.e., the DC powersupply 64 is turned on), and under the voltage output (and theassociated current) from the DC power supply 64, an electrolyticreaction occurs at the surface 17 of the resistor 14 to generatehydrogen ions, electrons, and oxygen ions 62 from the electrolyticsolution. The oxygen ions 62 chemically react with the portion 15 of theresistor 14 such that an oxidized region, such as the oxidized region 22depicted supra in FIG. 3, forms within the portion 15 of the resistor14. The generated hydrogen ions and electrons combine at the cathode 63to form hydrogen gas.

[0070]FIG. 7 shows the portion 16 of the resistor 14 above anelectrolyte level 67. Accordingly, FIG. 7 may exemplify a “partiallyexposed” embodiment in which the oxygen-unexposed portion 16 (see FIG.2) exists (i.e., S_(U)>0 and F<1). Alternatively, FIG. 7 may alsoexemplify a “totally exposed” embodiment in which the oxygen-unexposedportion 16 (see FIG. 2) does not exist (i.e., S_(U)=0 and F=1) if theresistor 14 is totally immersed in the electrolytic solution 61. Thus,FIG. 7 exemplifies either a “partially exposed” embodiment or a “totallyexposed” embodiment in which the oxygen-unexposed portion 16 (see FIG.2) exists or does not exist, respectively.

[0071] A thickness of the oxidized region (see, e.g., the thickness t ofthe oxidized region 22 described supra for FIG. 3) increases as a timeof the electrolytic reaction increases. As the thickness of the oxidizedregion increases, a current drawn by the anodizing bath 60 decreases dueto increasing isolation of the portion 15 of the resistor 14 from theelectrolytic solution 61 as the thickness of the oxidized layerincreases. For certain resistor 14 materials (e.g., aluminum), theanodization process may eventually self terminate, because said currentis eventually reduced to a negligible value.

[0072] The aforementioned method of oxidizing the resistor 14 usinganodization does not depend on the dimensions of the resistor 14 and isthus applicable if the portion 15 of the resistor 14 has dimensions of 1micron or less, and is likewise applicable if the portion 15 of theresistor 14 has dimensions in excess of 1 micron.1

[0073] As stated supra, anodization that causes nitridization of theresistor 14 could be used as an alternative to anodization that causesoxidation of the resistor 14. If anodization with nitridization isemployed instead of anodization with oxidation, then the electrolyticsolution 61 would include nitrogen instead of oxygen. An electrolytecontaining nitrogen that can be used depends on the electricallyresistive material to be anodized and is therefore case specific. Thus,any electrolyte containing nitrogen that is compatible with saidelectrically resistive material may be selected as would be known orapparent to one of ordinary skill in the art.

[0074] Chemical Oxidation

[0075]FIG. 8 illustrates a front cross-sectional view of a chemical bath70, in accordance with embodiments of the present invention. Thechemical bath 70 comprises a chemical solution 71. The semiconductorstructure 10 of FIG. 2 is immersed in the chemical solution 71. Thechemical solution 71 includes oxygen particles 72 in such form asoxygen-comprising liquid molecules, oxygen ions, or an oxygen-comprisinggas (e.g., oxygen gas or ozone gas) dissolved in the chemical solution71 under pressurization. The oxygen particles 72 chemically react withthe resistor 14 to form an oxidized region within the resistor 14 suchas the oxidized region 22 depicted supra in FIG. 3. A thickness of theoxidized region (see, e.g., the thickness t of the oxidized region 22described supra for FIG. 3) increases as a time of the chemical reactionincreases. The chemical reaction may be exothermic or endothermic,depending on the electrically resistive material of the resistor 14 andthe oxygen particles 72. If the chemical reaction is endothermic, anaddition of a sufficient amount of heat is required. Additionally, asuitable catalyst may be utilized to accelerate the chemical reaction.The catalyst may be any catalyst known to one of ordinary skill in theart for the particular chemical reaction.

[0076] Suitable resistor 14 electrically resistive materials for beingchemically oxidized include, inter alia, copper, tungsten, aluminum,titanium, nitrides thereof, and alloys thereof. Suitable chemicalsolutions 71 include, inter alia, hydrogen peroxide, ferric nitrate,ammonium persulphate, etc.

[0077]FIG. 8 shows the resistor 14 as totally immersed in the chemicalsolution 71, which exemplifies a “totally exposed” embodiment in whichthe oxygen-unexposed portion 16 (see FIG. 2) of the resistor 14 does notexist (i.e., S_(U)=0 and F=1), and the surface 17 is the total surface19 (see FIG. 1) that is oxidized in the chemical solution 71.Nonetheless, the resistor 14 could be rotated 90 degrees (within thecross-section plane illustrated in FIG. 8) and moved upward in adirection 75 such that a portion of the resistor 14 would be above thelevel 77 of the chemical solution 71 just as the portion 16 is above theelectrolyte level 67 in FIG. 7. Under such 90 degree rotation and upwardmovement, FIG. 8 would represent a “partially exposed” embodiment inwhich the oxygen-unexposed portion 16 (See FIG. 2) exists (i.e., S_(U)>0and F<1). Accordingly, FIG. 8 exemplifies either a “partially exposed”embodiment or a “totally exposed” embodiment in which theoxygen-unexposed portion 16 (see FIG. 2) exists or does not exist,respectively.

[0078] The aforementioned method of oxidizing the resistor 14 usingchemical oxidation does not depend on the dimensions of the resistor 14and is thus applicable if the resistor 14 has dimensions of 1 micron orless, and is likewise applicable if the resistor 14 has dimensions inexcess of 1 micron.

[0079] As stated supra, chemical nitridization of the resistor 14 couldbe used as an alternative to chemical oxidation of the resistor 14. Ifchemical nitridization is employed instead of chemical oxidation, thenthe chemical solution 71 would include nitrogen particles instead of theoxygen particles 72.

[0080] Resistance Testing

[0081] The resistor 14 may be tested prior to being oxidized ornitridized, while being oxidized or nitridized (i.e., in situ), and/orafter being oxidized or nitridized. The resistance testing may beaccomplished by a conventional test apparatus, such as with a four-pointresistance test having four contacts to the resistor with two of thecontacts coupled to a known current source outputting a current I andthe other two contacts coupled to a voltage meter that measures avoltage V across the resistance to be determined, and the measuredresistance is thus V/I. Alternatively, the resistance testing may beaccomplished with an inline measuring circuit within the same integratedcircuit that includes the resistor, wherein the measuring circuit iscoupled to instrumentation that outputs the measured resistance.

[0082]FIG. 9 illustrates FIG. 2 during exposure of the portion 15 of theresistor 14 to the oxygen particles 20, and with the resistor 14 coupledto an electrical resistance measuring apparatus 85. The electricalresistance measuring apparatus 85 may include the conventional testapparatus or the inline measuring circuit, mentioned supra. Theelectrical resistance measuring apparatus 85 may be conductively coupledto surfaces 81 and 82 of the resistor 14 by conductive interconnects(e.g., conductive wiring) 86 and 87, respectively. Accordingly, theelectrical resistance measuring apparatus 85 is capable of measuring anelectrical resistance of the resistor 14 (before, during, and afteroxidation or nitridization of the resistor 14) associated with currentflowing in the direction 7 through the resistor 14. Alternatively, theelectrical resistance measuring apparatus 85 may be used to measure anelectrical resistance of the resistor 14 associated with current flowingin the direction 6 through the resistor 14 (before, during, and afteroxidation or nitridization of the resistor 14) if the conductiveinterconnects 86 and 87 are coupled to bounding surfaces 83 and 84 ofthe resistor 14 instead of to the surfaces 81 and 82, respectively. Thesurface 83 in FIG. 9 corresponds to the surface 19 in FIG. 1. In FIG. 9,the resistor 14 includes an oxidized (or nitridized) region 21, whichcorresponds to the oxidized (or nitridized) region 22 of FIG. 3. Thesemiconductor structure 10 is within an oxidizing (or nitridizing)environment 80, which includes any oxidizing (or nitridizing)environment within the scope of the present invention such, inter alia,the heating chamber 30 of FIG. 4, the chamber 40 of FIG. 5, the plasmachamber 50 of FIG. 6, the anodization bath 60 of FIG. 7, and thechemical bath 70 of FIG. 8. The electrical resistance measuringapparatus 85 is any apparatus, as is known to one of ordinary skill inthe art, capable of measuring an electrical resistance of the resistor14.

[0083] The following discussion describes how the electrical resistancemeasuring apparatus 85 of FIG. 9 can be used for in situ testing tocontrol the electrical resistance acquired by the resistor 14 afterbeing exposed to the oxygen particles 20. The following discussionapplies to any of the embodiments described supra (i.e., thermaloxidation or nitridization using a heating chamber, thermal oxidation ornitridization using a directed beam of radiation or particles, plasmaoxidation/nitridization, anodization, and chemicaloxidation/nitridization).

[0084] Let R₁ denote an electrical resistance of the resistor 14 priorto being oxidized or nitridized. Let R₂ denote a final electricalresistance of the resistor 14 (i.e., an electrical resistance of theresistor 14 after being oxidized or nitridized). Let R_(t) denote apredetermined target electrical resistance with an associated resistancetolerance ΔR_(t) for the resistor 14 after the oxidation (ornitridization) has been completed (i.e., it is intended that R₂=R_(t)within the tolerance ΔR_(t)). The target electrical resistance R_(t) isapplication dependent. For example, in an analog circuit R_(t) may be afunction of a capacitance in the circuit, wherein for the givencapacitance, R_(t) has a value that constrains the width of a resonancepeak to a predetermined upper limit. In practice, the predeterminedresistance R_(t), together with the associated resistance toleranceΔR_(t), may be provided for the intended application.

[0085] The resistor 14 may have its electrical resistance tested duringor after the exposure of the resistor 14 to the oxygen particles 20. Asstated supra, the thickness t of the oxidized (or nitridized) region 22(see FIG. 3) increases as the time of said exposure increases, and theelectrical resistance of the resistor 14 increases as the thickness tincreases. Thus, the final electrical resistance may be controlled byselection of the time of exposure. The time of exposure may be selectedbased on any method or criteria designed to obtain R₂ as being withinR_(t)±ΔR_(t) (i.e., R_(t)−ΔR_(t)≦R₂≦R_(t)+ΔR_(t)). For example,calibration curves derived from prior experience may be used fordetermining the time of exposure that results in R₂ being withinR_(t)±ΔR_(t).

[0086] An iterative testing procedure may be utilized such that theelectrical resistance of the resistor 14 is tested during the exposingof the resistor 14 to the oxygen particles 20 and thus during theoxidizing (or nitridizing) of the resistor 14. The testing during theexposing of the resistor 14 to the oxygen particles 20 determinescontinuously or periodically whether R₂″ is within R_(t)+ΔR_(t), whereinR₂″ is the latest resistance of the resistor 14 as determined by thetesting. The testing is terminated if R₂″ is within R_(t)+ΔR_(t) or if(R₂″−R₁)(R_(t)−R₂″)≦0.

[0087] While particular embodiments of the present invention have beendescribed herein for purposes of illustration, many modifications andchanges will become apparent to those skilled in the art. Accordingly,the appended claims are intended to encompass all such modifications andchanges as fall within the true spirit and scope of this invention.

We claim:
 1. A method for increasing an electrical resistance of aresistor, comprising the steps of: providing a semiconductor structurethat includes the resistor; and oxidizing a fraction F of a surfacelayer of the resistor with oxygen particles, resulting in the increasingof the electrical resistance of the resistor.
 2. The method of claim 1,wherein F=1.
 3. The method of claim 1, wherein F<1.
 4. The method ofclaim 1, wherein a dimension of the portion of the resistor does notexceed about 1 micron.
 5. The method of claim 1, wherein the oxidizingstep includes: placing the semiconductor structure in a chamber;including a gas within chamber, wherein the gas includes the oxygenparticles at an oxygen concentration, and wherein the oxygen particlesinclude oxygen-comprising molecules; heating the fraction of the surfacelayer at a heating temperature, wherein a combination of an oxygenconcentration and the heating temperature is sufficient to oxidize thefraction of the surface layer; and oxidizing the fraction of the surfacelayer with the oxygen-comprising molecules.
 6. The method of claim 5,wherein the oxygen-comprising molecules are selected from the groupconsisting of molecular oxygen (O₂), nitrous oxide (N₂O), carbon dioxide(CO₂), and carbon monoxide (CO).
 7. The method of claim 5, wherein theresistor includes an electrically resistive material selected from thegroup consisting of polysilicon, amorphous silicon, titanium, tantalum,tungsten, aluminum, silver, copper, nitrides thereof, suicides thereof,and alloys thereof.
 8. The method of claim 5, wherein the chamberincludes a heating source, wherein the heating step includes heating aninterior of the heating chamber to the heating temperature by use of theheating source, wherein the heating of the interior of the heatingchamber includes the heating of the fraction of the surface layer, andwherein F=1.
 9. The method of claim 5, wherein heating the fraction ofthe surface layer includes directing a beam into the fraction of thesurface layer such that the beam causes the heating of the fraction ofthe surface layer, and wherein the beam is selected from the groupconsisting a beam of radiation and a beam of particles.
 10. The methodof claim 9, wherein the beam is the beam of radiation, and wherein theradiation includes a laser radiation.
 11. The method of claim 10,wherein F<1.
 12. The method of claim 10, wherein F=1.
 13. The method ofclaim 1, wherein F=1, and wherein the oxidizing step includes: providinga plasma chamber that includes a first electrode and a second electrode;disposing the semiconductor structure between the first electrode andthe second electrode; including a neutral gas within plasma chamber,wherein the neutral gas includes oxygen-comprising molecules; ionizingthe neutral gas to generate a plasma gas between the first electrode andthe second electrode, wherein the plasma gas includes the oxygenparticles as oxygen ions; accelerating with a direct current voltage theoxygen ions from the first electrode toward the second electrode,wherein the accelerated oxygen ions strike the resistor with an energythat is at least a threshold energy for oxidizing the surface layer ofthe resistor; and oxidizing the surface layer with the oxygen ions. 14.The method of claim 13, wherein the oxygen-comprising molecules areselected from the group consisting of molecular oxygen (O₂), nitrousoxide (N₂O), carbon dioxide (CO₂), and carbon monoxide (CO).
 15. Themethod of claim 13, wherein the resistor includes an electricallyresistive material selected from the group consisting of polysilicon,amorphous silicon, titanium, tantalum, tungsten, aluminum, silver,copper, nitrides thereof, suicides thereof, and alloys thereof.
 16. Themethod of claim 1, wherein the oxidizing step comprises: forming ananodization electrical circuit which includes: a DC power supply, anelectrolytic solution comprising oxygen, the resistor partially immersedin the electrolytic solution, and a cathode partially immersed in theelectrolytic solution, wherein the resistor is electrically coupled to apositive terminal of the DC power supply such that the resistor servesas an anode, and wherein the cathode is electrically coupled to anegative terminal of the DC power supply; activating the DC power supplysuch that the DC power supply generates a voltage output, wherein thevoltage output causes an electrolytic reaction in the electrolyticsolution near the resistor, wherein the electrolytic reaction generatesoxygen ions from the oxygen in the electrolytic solution, and whereinthe oxygen particles include the oxygen ions; and oxidizing the fractionof the surface layer with the oxygen ions.
 17. The method of claim 16,wherein F<1.
 18. The method of claim 16, wherein F=1.
 19. The method ofclaim 16, wherein the resistor includes an electrically resistivematerial selected from the group consisting of polysilicon, amorphoussilicon, titanium, tantalum, tungsten, aluminum, silver, copper,nitrides thereof, suicides thereof, and alloys thereof.
 20. The methodof claim 1, wherein the oxidizing step includes: providing a chemicalsolution which includes the oxygen particles, wherein the oxygenparticles are selected from the group consisting of oxygen-comprisingliquid molecules, oxygen ions, and an oxygen-comprising gas dissolved inthe chemical solution under pressurization; immersing the semiconductorstructure in the chemical solution; and oxidizing the fraction of thesurface layer of the resistor by chemically reacting the oxygenparticles with the fraction of the surface layer.
 21. The method ofclaim 20, wherein the resistor includes an electrically resistivematerial selected from the group consisting of copper, tungsten,aluminum, titanium, nitrides thereof, and alloys thereof.
 22. The methodof claim 20, wherein the chemical solution is selected from the groupconsisting of hydrogen peroxide, ferric nitrate, and ammoniumpersulphate.
 23. The method of claim 1, further comprising: providing apredetermined target resistance in terms of a value R_(t) and atolerance ΔR_(t) for the electrical resistance of the resistor; andtesting the resistor during the oxidizing step to determine whether theelectrical resistance of the resistor is within R_(t)±ΔR_(t).
 24. Themethod of claim 23, wherein during the testing step the electricalresistance of the resistor is determined to not be within R_(t)±ΔR_(t),and further comprising iterating such that each iteration of theiterating includes additionally testing the resistor during theoxidizing step to determine whether R₂″ is within R_(t)±ΔR_(t), andending the iterating if R₂″ is within R_(t)±ΔR_(t) or if (R₂″−R₁)(R_(t)−R₂″)<0, wherein R₁ is an electrical resistance of the resistorprior to the oxidizing of the portion of the resistor, and wherein R₂″is a latest value of the electrical resistance of the resistor asdetermined by the testing.
 25. An electrical structure, comprising: asemiconductor structure that includes a resistor; and oxygen particlesin an oxidizing reaction with a fraction F of a surface layer of theresistor, wherein the oxidizing reaction increases an electricalresistance of the resistor.
 26. The electrical structure of claim 25,wherein F=1.
 27. The electrical structure of claim 25, wherein F<1. 28.The electrical structure of claim 25, wherein a dimension of thefraction of the resistor does not exceed about 1 micron.
 29. Theelectrical structure of claim 25, further comprising: a chamber in whichthe semiconductor structure has been placed; a gas within the chamber,wherein the gas includes the oxygen particles at an oxygenconcentration, and wherein the oxygen particles includeoxygen-comprising molecules; the fraction of the surface layer beingheated at a heating temperature, wherein a combination of an oxygenconcentration and the heating temperature is sufficient to oxidize thefraction of the surface layer; and the fraction of the surface layerbeing oxidized by the oxygen-comprising molecules.
 30. The electricalstructure of claim 29, wherein the oxygen-comprising molecules areselected from the group consisting of molecular oxygen (O₂), nitrousoxide (N₂O), carbon dioxide (CO₂), and carbon monoxide (CO).
 31. Theelectrical structure of claim 29, wherein the resistor includes anelectrically resistive material selected from the group consisting ofpolysilicon, amorphous silicon, titanium, tantalum, tungsten, aluminum,silver, copper, nitrides thereof, silicides thereof, and alloys thereof.32. The electrical structure of claim 29, wherein the chamber includes aheating source, wherein an interior of the heating chamber is beingheated at the heating temperature by use of the heating source, whereinthe heating of the interior of the heating chamber includes the surfacelayer being heated at the heating temperature, and wherein F=1.
 33. Theelectrical structure of claim 29, wherein the fraction of the surfacelayer is being heated by a directed beam which imparts energy into thefraction of the surface layer, and wherein the beam is selected from thegroup consisting a beam of radiation and a beam of particles.
 34. Theelectrical structure of claim 33, wherein the beam is the beam ofradiation, and wherein the radiation includes a laser radiation.
 35. Theelectrical structure of claim 34, wherein F<1.
 36. The electricalstructure of claim 34, wherein F=1.
 37. The electrical structure ofclaim 25, wherein F=1, and further comprising: a plasma chamber thatincludes a first electrode and a second electrode; the semiconductorstructure disposed between the first electrode and the second electrode;a plasma gas between the first electrode and the second electrode,wherein the plasma gas includes the oxygen particles as oxygen ions, andwherein the oxygen ions have been formed from an ionization ofoxygen-comprising molecules in a neutral gas within the plasma chamber;the oxygen ions being accelerated from the first electrode toward thesecond electrode and into the resistor with an energy that is at least athreshold energy for oxidizing the surface layer of the resistor,wherein the oxygen ions are being accelerated by a direct currentvoltage; and the surface layer being oxidized by the oxygen ions. 38.The electrical structure of claim 37, wherein the oxygen-comprisingmolecules are selected from the group consisting of molecular oxygen(O₂), nitrous oxide (N₂O), carbon dioxide (CO₂), and carbon monoxide(CO).
 39. The electrical structure of claim 37, wherein the resistorincludes an electrically resistive material selected from the groupconsisting of polysilicon, amorphous silicon, titanium, tantalum,tungsten, aluminum, silver, copper, nitrides thereof, silicides thereof,and alloys thereof.
 40. The electrical structure of claim 25, furthercomprising: an anodization electrical circuit, including: a DC powersupply, an electrolytic solution, the resistor partially immersed in theelectrolytic solution, and a cathode partially immersed in theelectrolytic solution, wherein the resistor is electrically coupled to apositive terminal of the DC power supply such that the resistor servesas an anode, and wherein the cathode is electrically coupled to anegative terminal of the DC power supply; a voltage output from the DCpower supply, wherein the voltage output causes an electrolytic reactionin the electrolytic solution near the resistor, wherein the electrolyticreaction generates oxygen ions, and wherein the oxygen particles includethe oxygen ions; and the fraction of the surface layer being oxidized bythe oxygen ions.
 41. The electrical structure of claim 40, wherein F<1.42. The electrical structure of claim 40, wherein F=1.
 43. Theelectrical structure of claim 40, wherein the resistor includes anelectrically resistive material selected from the group consisting ofpolysilicon, amorphous silicon, titanium, tantalum, tungsten, aluminum,silver, copper, nitrides thereof, silicides thereof, and alloys thereof.44. The electrical structure of claim 25, further comprising: a chemicalsolution including the oxygen particles, wherein the oxygen particlesare selected from the group consisting of oxygen-comprising liquidmolecules, oxygen ions, and an oxygen-comprising gas dissolved in thechemical solution under pressurization. the semiconductor structureimmersed in the chemical solution; and the fraction of the surface layerof the resistor being oxidized by a chemical reaction between the oxygenparticles and the fraction of the surface layer.
 45. The electricalstructure of claim 44 wherein the resistor includes an electricallyresistive material selected from the group consisting of copper,tungsten, aluminum, titanium, nitrides thereof, and alloys thereof. 46.The electrical structure of claim 44, wherein the chemical solution isselected from the group consisting of hydrogen peroxide, ferric nitrate,and ammonium persulphate.
 47. A method for increasing an electricalresistance of a resistor, comprising the steps of: providing asemiconductor structure that includes the resistor; and nitridizing afraction F of a surface layer of the resistor with nitrogen particles,resulting in the increasing of the electrical resistance of theresistor.
 48. An electrical structure, comprising: a semiconductorstructure that includes a resistor; and nitrogen particles in annitridizing reaction with a fraction F of a surface layer of theresistor, wherein the nitridizing reaction increases an electricalresistance of the resistor.